A 61 year old man complains of a "fluttering feeling" in his chest for the last hour. He is mildly anxious, but denies dizziness or faintishness. No other symptoms are present. He has experienced several such episodes over the last 2 months. He was diagnosed with hypertension 10 years ago, but was poorly compliant with his treatment. He does not smoke and only drinks socially. A full blood count and electrolytes are found to be normal.
The rate is 114 bpm, with an irregular rhythm. The baseline is irregular and p waves are absent.
The x-ray appears normal.
TSH: 0.01 mIU/l (very low) Free T3: 8.7 pg/mL (high) Free T4: 12.3 ng/l (high)
Left ventricular hypertrophy is noted. Cardiac contractions are irregular, but systolic function is normal with an ejection fraction of 56%. No left atrial thrombi are seen and no regional ventricular wall motion abnormalities are noted.